Document Type : Research Article
Authors
1
Biomedical Engineering Faculty, Yazd Branch, Islamic Azad University, Yazd, Iran
2
Department of Chemical and Polymer Engineering, Yazd University, Yazd, Iran
3
Central Iran Radiation Processing Complex, Nuclear Science and Technology Research Institue, Yazd, Iran
Abstract
In this study, the effect of electron beam (EB) irradiation of shrimp shells as well as the time and concentration of HCl and NaOH on the process of chitin extraction and chitosan production, were investigated. The products characteristics were evaluated by Fourier-transform infrared spectroscopy, atomic absorption spectroscopy, X-ray diffraction spectroscopy, thermogravimetric analysis, viscosity measurement, water and fat binding capacity determination and antimicrobial analysis. The extent and rate of demineralization and deproteinization increased initially by increasing of HCl and NaOH concentrations, respectively, and then leveled off. According to the results, demineralization with 0.5 M HCl for 6 h and deproteinization with 1.0 M NaOH at 65 °C for 6 h were proposed as suitable procedure for chitin extraction. EB irradiation of shrimp shells, in the range of 10-99 kGy, led to a decrease in the time required for both demineralization and deproteinization processes. Remained calcium in unirradiated and 30 kGy irradiated shells, after 6 h treatment with 0.5 M HCl, were 13.75 and 9.75 mg/g, respectively. Increasing of irradiation dose, led to a decrease in molecular weight (MW), an increase in deacetylation degree (DD) and a decrease in the crystallinity of chitosan. Depending on the irradiation dose and deacetylation reaction conditions, chitosan with DD varied between 60-95% and MW varied between 2.1×105-2.3×104 were produced. MIC and MBC of resultant chitosan samples, varied between 0.6-0.8 and 1.4-2.5 g/L against E. coli, as well as between 0.5-0.70 and 0.8-1.5 g/L against S. aureus, respectively. With increasing irradiation dose from 0 to 99 kGy, the diameter of inhibition zone against E. coli and S. aureus increased from 3.7 to 17.2 and from 5 to 18.8 mm, respectively. According to the results, it seems that EB irradiation is a promising method for producing chitin and chitosan with unique properties suitable for different applications.
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